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# escape velocity

the minimum speed that an object at a given distance from a gravitating body must have so that it will continue to move away from the body instead of orbiting about it.
[1950-55]

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Speed sufficient for a body to escape from a gravitational centre of attraction without accelerating further.

It decreases with altitude and equals the square root of 2 (about 1.414) times the speed needed to maintain a circular orbit at the same altitude. At the surface of Earth, disregarding atmospheric resistance, escape velocity is about 6.96 mi/second (11.2 km/second). Escape velocity from the surface of the Moon is about one-third of this.

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in astronomy and space exploration, the velocity that is sufficient for a body to escape from a gravitational centre of attraction without undergoing any further acceleration. Escape velocity decreases with altitude and is equal to the square root of 2 (or about 1.414) times the velocity necessary to maintain a circular orbit at the same altitude. At the surface of the Earth, if atmospheric resistance could be disregarded, escape velocity would be about 11.2 km (6.96 miles) per second. The velocity of escape from the less massive Moon is about 2.4 km per second at its surface. A planet (or satellite) cannot long retain an atmosphere if the planet's escape velocity is low enough to be near the average velocity of the gas molecules making up the atmosphere.

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Universalium. 2010.

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